How to Reset a Comcast Cable Modem's IP Address

Comcast provides high-speed Internet connections over the same RF coaxial cable network used for television services. Cable Internet connections work by using the unused frequencies available on the RF coaxial cables for data transfer. The coaxial cable is connected to a cable modem, which then converts the Internet signal to Ethernet. The Comcast cable modem is designed to connect to a single Ethernet device, such as a computer or router. The device's Media Access Control, or MAC address, is recorded, and an IP address is assigned to that MAC address. You can reset the IP address assigned to you through the Comcast cable modem by temporarily changing the connected Ethernet device.

Instructions

1. Power off the Comcast cable modem. If you also receive phone service in addition to Internet service, disconnect the battery inside the cable modem.

2. Connect a different device, such as a different computer, to the cable modem's Ethernet port with an Ethernet cable.

3. Power on the cable modem and wait two minutes for the signal to synchronize.

4. Power off the cable modem again.

5. Connect the original Ethernet device to the cable modem.

6. Power on the cable modem and wait two minutes for the signal to synchronize. The IP address is now changed. Be sure to reconnect the cable modem's battery, if one is present.

Tips & Warnings

• Even though the original device is being reconnected to the cable modem, by temporarily connecting a different device to the cable modem, the MAC-to-IP address mapping is changed ,which resets the assigned IP address.

• Ethernet networking uses Media Access Control addresses as hardware addresses tied to each Ethernet networking card. MAC addresses are 48 bits in length, with the first 24 bits representing the Ethernet card manufacturer, and the second 24 bits representing a unique number assigned by the card manufacturer. This ensures all Ethernet cards produced have a globally-unique hardware address.